Wireless communications systems, for example packet based communications systems, may provide voice telephony using the Voice-over-Internet-Protocol (VoIP). Any historical demarcation between “data” and “voice” has become blurred in packet based communications systems such that the term “data” usually signifies payload information for any service, whether voice, or data such as may be provided by downloading from the Internet.
Differences remain however, in that voice will generally employ smaller packet sizes, for example due to delay sensitivity, than would traditional so-called data. For, example a non-voice data packet may be larger than a kilo-byte while a voice packet may be only approximately 15 to 50 bytes depending upon the vocoder rate employed.
Because of the smaller packet sizes utilized by voice sessions, a greatly increased number of voice users may be served thereby placing a burden on the control mechanisms and resources of the communications system.
However, RTP/UDP/IP (Real-Time Transport protocol/User Datagram Protocol/Internet protocol) overhead is added to each vocoder packet, in addition to Cyclic Redundancy Check (CRC) bits, etc. Systems that employ Hybrid Automatic Repeat Request are further burdened by such protocol overhead in addition to control requirements.
HARQ may make use of persistent channels for retransmissions, however such control resources require additional processing and transmission and therefore consumes even more resources which would have been available for voice traffic thus further burdening the network.
Thus, there is a need for providing mobile stations with resources for HARQ retransmissions without persistent assignments and without significantly increasing the overhead of the communication system.